In a couple of places in the sequence where there are two or more visible layers overlapping with top layer/s having less than 100% opacity there is some unwanted 'extra' colours appearing which can be seen in the attached image below.

In the left image the unwanted colour appears in the center above the mans head, it is grey coloured.

In the right image the unwanted colour is the red.

All blending modes are Normal. There are Track Mattes in use. There are RGB curves being used.

As a result of trying to gather pertinent information for this post I found a cure, hahaha.

For the left images situation I found that turning the RGB curves off removed the colours, so I replaced the curves with Levels and the issue went away...

So for the right images situation I added a levels below the track matte and above the RGB curves, and the issue went away, no adjustment to the levels at all... I moved the levels from between the Track Matte and the Curves and the issue reapeared.